BYU professor Steven Jones may well be what passes for an expert in his oddly paired specialties of "metal-assisted (cold) fusion" and ancient American horses, but I see nothing in his BYU faculty listing that would incline me to look to him for expert analysis of the collapse of the World Trade Center during the 9/11 attacks. In fact, not to put too fine a point on it, I see signs of a kooky dilettante diminishing the credibility of my BYU degree.
I'll let the credentialed specialists in mechanical physics and civil engineering refute Jones' specific arguments (most of which I've seen before on various conspiracy-theory Web sites), but concerning the "squibs," or puffs of smoke and debris below the main body of collapsing debris as the WTC buildings collapsed, as the towers' upper floors first failed and struck the floor immediately below the failure, the shock of that initial collapse would have propagated downward through the structure at roughly the speed of sound through metal. That would transfer a massive amount of energy downward — more than enough to probably cause lower floors to fail even before the main debris body actually landed on them.
Costa Mesa, Calif.